Remote control system



-UAKE$ BEFOHL' 2G BREAKS ONOPERATE MAKES BEFORE 20 BREAKS 0V RELEASE IIAKESBEFOfiE/Z [IREAKSGVRELEASE Filed Aug. 25, 1942 Der, 5, 1944.

lNVENTOR F C. GR/ESE B)".

ATTORNEY 1 TILEPHON! Patented Dec; 5, 1944 REMOTE CONTROL SYSTEM Frank O. Griese, Plainfield, N. J., assignor to Bell Telephone Laboratories,

Incorporated, New

York, N. Y., a corporationof New York Application August 25, 1942, SerialNo. 456,002

4 Claims. 175-320) This invention relates to radio communication systems and more particularly to facilities for providing two-way communication at a telephone station-via land wires and a distant radio receiver and transmitter, employing a so-called I closed loop-channel for controlling from the telephon'e'station the connection of either the radio transmitter or theradio rece'iverto the telephone station viathe land wires.

Specifically the invention relates to means, including an auxiliaryclosed loop channel to enable I an intermediate telephone station, off the route station MS connectedby means of a speech transmission line "L, anda closed loop switching control circuit TL, with a distant radio switching point-RC shown-tothe right of the vertical broken line H. Intermediate the broken lines AA and XX is shown an intermediate -switching point iBP on the route of the lines L and'TL from which point a line IL extends to 'an'intermediat telephone station IS below the broken line YY'.

"Referring to the drawing itwill be understood that the speech transmission 'line L is normally connected, as-shown,'to the radio receiver circuit over the normal or back contact of the control relay I and is connected to the radio transmitter 1 by operation of this relay.

When the telephone at the main station MS is connected to the line L, as for example by oper ating the listening key or switch 2, which causes relay 3 to operate and close its armature contacts, the attendant can listen or receive speech signals incoming over the line L from the distant radio receiver. When the attendant desires to talk, i. e., to send out speech signals from the distant radio transmitter, he operates the socalled press-to-talk button or key 2|, usually located at a convenient point on the telephone instrument, thereby energizing his transmitter T in series with relay 4 in a circuit which is obvious. Relay 4 in'operating closes a circuit to operate relay 5 which by closing its contacts 6 lights pilot lamp 1 at the station MS and by opening its contacts 8 opens the normal closed switching control circuit TL which permits relay 9 at the distant radio control point RC to release which in turn causes relay *I to-operate to transfer the speech transmission line L from the radio receiver to the radio transmitter. Itwill be noted that when the arrangement of the present circuit is put in service initially relays I0, I I, I3, I! and I9 assume the'condition shown on the drawing. When switching loop 'TL is opened relay I0, in series therewith at point BP, releases thereby deenergizing normally operated relay II which is so constructed and arranged that its contact22 makes before its contact I2 breaks on release of the relay the purpose of which is to insure that a holding circuit for relay I9 is closed before contact I 2 opens to release-relay I3, which is in series with an auxiliary simplex signaling circuit superimposed on the speech transmission line IL bridged across the main line'L at the point'BP and leading to an intermediate station IS, as

otherwise relay I9 would release responsive to the release of relay I3 and, by opening its contacts 2!], permit the opening of the main switching Opening the auxiliary simplex circuit at contacts I2 of relay II also causes relay I4 at'the "intermediate station to release which latter relay in releasing lights busy pilot lamp I5 thereat as an indication that the radio circuit is in use at the main station MS, i. 'e., that the attendant thereat has press-to-talk key 21 operated.

Relay I I at the bridging point BP, in releasing,

also closes its contact I6 thereby operating relay I! which performs'no'useful function atthis time.

Reclosure of the signalcontrolloop TL and the consequent reoperation of relay Ill, occasioned by the attendant at station MS releasin the press-to-talk key 2|, closes its contacts in a circuit to reoperate relay IIwhich can be traced from ground, contacts 35 of relay I9, contacts 36 of relay I1, and contacts of relay III to battery in series with relay II. Relay II operated opens its contacts I6 to open the circuit of relay I'I, recloses the auxiliary signal circuit at contacts I2 to operate relay I3 and removes ground from its contacts 22. Relay I1 is constructed so that it is slow to release thus guarding against the release of relay I9 if for any reason relay I3 fails to close its contacts before relay I I opens its contacts 22. Reclosure of the auxiliary signal circuit reoperates relay I4 at the intermediate station thereby extinguishing the pilot lamp I5.

If the telephone set at the intermediate station IS is connected to the line by operation of the key 23, thereby establishing it in a listening or receiving condition, and the attendant wishes to control the distant radio transmitter, he will operate the press-to-talk key 24 thereby operating relay 25, and in turn relay 26, which closes its contacts 32 to light pilot lamp 33. Relay 26 also opens its contact 2! to open the simpleX circuit superimposed on line IL which releases relay |3 at the bridging point BP.

Release of relay l3 removes ground from relay l9 which relay is constructed in the same manner as relay H to insure that a holding circuit for relay H is maintained at its contacts 28. If this guard condition was not provided release of relay 19 would open the signal loop 'I'L at its contacts 20 thereby releasing relay l which, by opening its contacts, would release relay -II thus permanently opening the auxiliary signal circuit at its contacts l2. Relay l9 released opens at its contacts 20 the normally closed signal loop TL which acts as before described to transfer the speech line L from the radio receiver to the radio transmitter by releasing relay 9. Relay l9 further closes its-contacts 29 thus energizing relay I! which operates but accomplishes no function immediately.

When the loop circuit TL is opened, relay 30, at the station MS releases thereby causing pilot lamp 3| thereat to light as a signal that the intermediate station IS has taken control of the radio transmitter.

When the key 24 at station IS is released, re-

lay 26 releases followed by the reoperation of relays l4 and I3. Relay 13 in operating recloses the circuit of relay I9 which operates and closes, at its contacts 20, the signal loop TL and also opens its contacts 29 thereby opening the operating circuit for relay I l which relay however is slow to release and therefore maintains its contacts 34 closed for an interval sufllcient to hold relay ll operated until relay ID in series in the signal loop has fully operated. Closure of the loop also operates relay 3!! which extinguishes pilot lamp 3|.

What is claimed is:

1. In a switching system, an originating station, a terminal station, a closed loop circuit therebetween, switching means at the originating station for opening said loop circuit thereat, a third station, a second closed loop circuit extending from said third station to a point in said first loop intermediate said originating and terminal stations, switching means at the third station for opening said second loop thereat, switching means responsive to opening and closing said first loop at the originating station to open and close said second loop and other switching means responsive to opening and closing said second loop at the third station to open and close the first loop.

2. In a remote control system, a first control station, a controlled station including a controllable device thereat, a first closed loop circuit therebetween serially including a source of potential and said controllable device, switching means at the first control station for Opening said loop circuit thereat, a second control station, a second closed loop circuit, including a second source of potential, extending from said second control station to a switching point in said first loop intermediate said controlled station and said first control station, switching means at the second control station for opening said second loop thereat, switching means responsive to opening and closing of said first loop at the first control station to open and close said second loop and other switching means responsive to opening and closing said second loop at the second control station to open and close the first loop.

3. In a signaling system, an originating station, a terminal station, a line therebetween, serially including a source of potential, switching means controlled at the originating station for normally closing said line thereat adapted when operated to open said line, electromagnetic switching devices in series with said line at the terminal station, a station intermediate said originating and terminal station, switching means controlled from said intermediate station for opening said line at a second point and means in said line responsive to opening said line at the originating station to prevent opening the line at said second point.

4. In a signaling system, an originating station, a terminal station, a line therebetween, means controlled at the originating station for normally closing the line thereat and adapted when operated to open the line, an electroresponsive device in series with said line at the terminal station, a station intermediate said originating and terminal station, intermediate switching means controlled from said intermediate station for opening said line at a second point and means in said line, responsive to operation of said means at the originating station while the line is closed at the second point for disabling said intermediate switching means and insure continuity of said line at the second point.

FRANK C. GRIESE. 

